Golang : How to verify input is rune?

Problem :

You need to determine if the user input is a valid rune. How to do that?

Solution :

Use unicode/utf8.Valid() function to check if the user input is a valid rune.

For example,

 package main

 import (
  "fmt"
  "unicode/utf8"
 )

 func main() {
  valid := []byte("Hello, 世界")
  invalid := []byte{0xff, 0xfe, 0xfd}

  fmt.Println(utf8.Valid(valid))
  fmt.Println(utf8.Valid(invalid))
 }

Output :

true

false

NOTE :

Depending on the input stream type, use utf8.Valid() for handling byte array, utf8.ValidRune() is for handling single rune and use utf8.ValidString() for handling string.

References :

https://golang.org/pkg/unicode/utf8/#Valid

https://golang.org/pkg/unicode/utf8/#ValidRune

https://golang.org/pkg/unicode/utf8/#ValidString